JPS5858664B2 - Toner for electrostatic image development and image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc., and an image forming method using the toner.

Methods for developing electrostatic images are broadly divided into the so-called liquid development method, which uses a developer in which various pigments and dyes are finely dispersed in an insulating organic liquid, the cascade method, the bristle brush method, the magnetic brush method, and the impression method. There are so-called dry development methods that use a fine powder developer called toner, which is a natural or synthetic resin containing a coloring agent such as carbon black dispersed therein, such as the powder cloud method and the powder cloud method. Regarding the toner used.

After developing an electrostatic charge image using toner, fixing is performed. Generally, fixing involves directly fusing the toner image obtained by development onto a photoconductive photoreceptor or electrostatic recording medium that carries the electrostatic charge image. This is done by first transferring the toner image obtained by attaching or developing it from a photoconductive photoreceptor or electrostatic recording medium onto a transfer sheet such as paper, and then fusing it onto the transfer sheet. .

At this time, the toner image is fused either by contact with solvent vapor or by heating, and the heating methods generally include a non-contact heating method using an electric furnace and a compression heating method using a heating roller.

The pressure heating method using a heating roller performs fixing by passing the toner image surface of the sheet to be fixed through pressure contact with the surface of a heating roller whose surface is made of a material that has releasability for toner. Generally called the heating roller fixing method, this method brings pressure contact between the surface of the heating roller and the toner image surface of the sheet to be fixed, so the thermal efficiency when fusing the toner image onto the sheet to be fixed is extremely high. It is very suitable for use in transfer-type electrophotographic copying machines, especially for high-speed copying, because it has good properties and can perform fixing quickly.

However, in this method, since the surface of the fixing roller and the toner particles come into pressure contact in a heated and molten state, some of the toner particles adhere to the surface of the fixing roller and are transferred, and then transferred again onto the next sheet to be fixed. This may cause a so-called offset phenomenon and stain the sheet to be fixed.

Therefore, one of the essential requirements in the heated roller fixing method is to prevent toner from adhering to the roller surface.

Conventionally, in order to prevent toner from adhering to the surface of the fixing roller,
For example, the roller surface is formed of a material such as a fluorine-based resin that has excellent releasability for toner, and an offset prevention liquid such as silicone oil is further supplied to the surface to coat the roller surface with a thin film of liquid. is being carried out.

Although this method is effective in preventing toner offset, it generates an odor due to heating of the offset prevention liquid and requires a device to supply the offset prevention liquid. As the mechanism of the copying machine becomes more complex, high precision is required to obtain stable results, which makes the copying machine expensive.

However, if the offset prevention liquid is not supplied, toner adheres to the surface of the fixing roller and an offset phenomenon occurs, so despite these drawbacks, it is currently necessary to supply offset prevention liquid. It is.

Therefore, in order to avoid these problems, Japanese Patent Application Laid-Open No. 501346
No. 52, JP 50-144446 and Special Edition 50-3
Toner resins and toners described in Publication No. 304, etc. have been developed, but even when such toner resins and toners are used, it is difficult to visually inspect when making a large number of copies with an actual copying machine. In this case, toner due to a slight offset phenomenon that cannot be detected gradually accumulates on the surface of the fixing roller, and the fixing roller becomes smeared with the toner, resulting in a disadvantage that the quality of the copied image deteriorates.

Additionally, when the temperature of the fixing roller decreases as a result of copying a large number of sheets, a phenomenon called "wrapping" occurs in which the transfer sheet supporting the toner particles wraps around the upper fixing roller. In order to prevent this, the current state is that the fixing device is equipped with a separation mechanism such as a stopper.

However, when such a separation mechanism is used, a drop in image quality called "separation scratches" occurs due to forcibly peeling off the transfer sheet with the stopper on the copy image, and sometimes the stopper However, the transfer sheet may not be separated from the roller and the transfer sheet may not be ejected.

The above problems negate the various advantages obtained by not supplying an anti-offset liquid.

The present invention eliminates the above drawbacks and eliminates the toner offset phenomenon and the wrapping phenomenon of the transfer sheet around the upper fixing roller even when using a fixing roller that does not supply offset prevention liquid to the surface of the fixing roller. It is an object of the present invention to provide a toner for electrostatic charge one-phenomenon effect that can efficiently perform good fixing with a heating roller.

That is, as a result of various studies based on the conventional knowledge of imparting non-offset properties to toner, the present invention uses a styrenic polymer or styrene monomer having a weight average molecular weight/number average molecular weight of 3.5 or more as a toner resin. Polyalkylene having a weight average molecular weight of 1,000 to 45,000 among various mold release agents is used in combination with a copolymer of polymer and other vinyl monomers in an amount of 1 to 25 parts by weight per 100 parts by weight of the resin component. It has been found that this is particularly effective in preventing toner offset.

Furthermore, it has been found that by using the toner of the present invention, it is possible to prevent a phenomenon called "wrapping" of the transfer sheet around the upper fixing roller.

When using a heated roller fixing device, generally (this offset phenomenon occurs when the temperature of the fixing roller is high, and the temperature at which this offset phenomenon occurs determines the practical upper limit temperature of the fixing device of the fixing device, On the other hand, the above-mentioned phenomenon of the transfer sheet wrapping around the upper fixing roller occurs when the temperature of the fixing roller is low, and determines the practical minimum fixing temperature.

Therefore, when using a heated roller fixing device, the temperature of the fixing roller must be controlled within a certain temperature range determined by the above-mentioned offset phenomenon and wrapping phenomenon.
By using the toner of the present invention, the non-offset property of the toner can be improved and the wrapping phenomenon of the transfer sheet can be prevented. No winding phenomenon occurs, the control range of the fixing roller temperature is significantly expanded, restrictions on temperature control are significantly reduced, and a stable image can always be maintained.

Furthermore, since no offset prevention liquid is supplied, the mechanism of the fixing device can be simplified, and the accuracy, stability, and reliability of, for example, high-speed copying machines incorporating such a fixing device can be improved. Furthermore, the cost can also be reduced.

Therefore, it has the advantage of making the design of an ultra-high speed copying machine extremely easy.

Generally, toners are made of resin components, colorant components such as pigments or dyes, and additive components such as plasticizers and charge control agents to adjust the physical properties and development characteristics of the toner.
As the resin component, various natural or base resins and polymers are used alone or in an appropriate mixture.

In some cases, a polymer which is colored itself to which a dye is bound may also be used as the grain component.

In the toner of the present invention, a polymer consisting only of styrene monomers or a copolymer of styrene monomers and other vinyl monomers is used as the resin component.

Examples of styrenic monomers include styrene, 0-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2°4-dimethylstyrene, p
-'-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene , p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3
4-dichlorostyrene is mentioned, with styrene monomer being most preferred.

Other vinyl monomers include, for example, ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, and isobutylene; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide, and vinyl fluoride; vinyl acetate, propion Vinyl esters such as vinyl acid, vinyl benzoate, vinyl butyrate, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate,
Dodecyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, methyl α-chloroacrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, n-butyl methacrylate, n-butyl methacrylate, dodecyl methacrylate, methacrylonitrile, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, diethylamine methacrylate α-Methylene aliphatic monocarboxylic acid esters such as ethyl and diethylamine ethyl methacrylate; Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide; Vinyl ether of vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether Vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, methyl isopropenyl ketone; N-
Examples include N-vinyl compounds such as vinylpyrrole, N-vinylcarbazole, N-vinylindole, and N-vinylpyrrole; and vinylnaphthalenes.

Note that the styrene resin according to the present invention includes those formed by acetalizing a polymer such as polyvinyl acecures such as polyvinyl butyral.

The styrenic resin according to the present invention can be obtained by arbitrarily combining the above-mentioned styrene monomer and other vinyl monomers, but styrene monomer is effective as the styrene monomer,
As other vinyl monomers, α-methylene aliphatic monocarboxylic acid esters are effective, and copolymers of styrene monomer and α-methylene aliphatic monocarboxylic acid ester are particularly effective.

Furthermore, a resin containing α-methylene aliphatic monocarboxylic acid esters as a monomer component and at least about 30 mol% of styrene monomer not only does not cause toner offset phenomenon, but also is required as a toner. The manufacturing process properties such as triboelectric charging properties, crushability, and uniform dispersion of additives are also excellent, and the four swords of the present invention are particularly effective for &σ.

The styrenic resin according to the present invention has a Mw/Mn value of 3.5 or more, but preferably has an Mw/Mn value of 5 or more, and has a molecular weight of about 2000 to 3000 in Mn.
Particularly desirable are those having a value of 0.

Note that the values of Mw, Mn, and Mw/Mn can be measured by various methods, and there are slight variations depending on the measurement method.

Therefore, in the present invention, Mw, Mn and Mw/
The value of Mn is defined as that measured by the following measuring method.

That is, all of these values are values measured by gel permeation chromatography under the conditions described below.

The solvent (tetrahydrofuran) was flowed at a flow rate of 17711 per minute at a temperature of 25°C, and 8 m9 of a tetrahydrofuran sample solution with a concentration of 0.497 di was injected as a sample weight.
Take measurements.

When measuring the molecular weight of a sample, the measurement conditions are such that the molecular weight distribution of the sample is within a range where the logarithm of the molecular weight and the count number of the calibration curve prepared using several types of monodisperse polystyrene standard samples are linear. select.

In addition, the reliability of this measurement was determined using the NB5706 polystyrene standard sample (Mw = 28.8
X 104, Mn=13.7X104, Mw/Mn
= 2.11) is confirmed by Mw/Mn being 2.11±0410.

In the present invention, the objective can be achieved by using a styrene resin with an Mw/Mn of 3.5 or more, and a styrene resin with an Mw/Mn of 5 or more is particularly effective in preventing offset.

Furthermore, although the styrenic resin according to the present invention differs depending on the type of monomer contained as a constituent part, in general, those having a softening point of about 100 to 170°C by the ring and ball method are particularly effective, and Furthermore, those having a glass transition point of 40° C. or higher are particularly effective.

That is, when the softening point is 100° C. or lower, excessive pulverization is likely to occur, and the photoconductive plate is likely to be contaminated due to toner filming.

Further, if the softening point exceeds 170° C., it is hard and difficult to crush, and a large amount of heat is required during fixing, resulting in poor fixing efficiency.

On the other hand, when the glass transition point is 40° C. or lower, agglomeration is likely to occur due to the cold flow phenomenon since the storage condition for toner is usually 40° C. or lower.

In addition, the glass transition point of styrene resin is generally Mw/M
As the value of n increases, it tends to vary and it is difficult to show a specific value, so it may be difficult to measure the glass transition point of a resin with a variable Mw/Mn value.

The styrene resin according to the present invention can be synthesized by the following method.

When using a general polymerization method, Mw/Mn is 1.5 to 3.0
of resin is obtained.

However, in order to obtain a resin having Mw/Mn of 3.5 or more used in the present invention, the following method is used.

That is, one method is to carry out polymerization by changing the polymerization temperature continuously or intermittently.

Another method is to polymerize a divinyl compound and a trivinyl compound in combination.

Still another method is a method in which several types of monomers having different initiator concentrations and chain transfer agent concentrations are sequentially added and polymerized.

In particular, a resin with a large Mw/Mn can be easily obtained by mixing a relatively low molecular weight resin with a high molecular weight resin.

These methods include bulk polymerization, melt polymerization, suspension polymerization,
This can be done by emulsion polymerization method.

However, the suspension polymerization method is most preferable due to the ease of handling of the resin obtained and the reduction in manufacturing costs.

In addition, one method for increasing Mw/Mn is to dissolve several types of resins with different molecular weights in a solvent and remove the solvent by drying under reduced pressure or spray drying, or to melt and blend by heating. be.

However, in order to obtain the desired effects of the present invention, it is preferable that the particles be homogeneously dispersed.

The method for producing styrenic resin according to the present invention is described, for example, in British Patent No. 1,495,428.

The weight average molecular weight used in the toner of the present invention is 1
000 to 45,000 polyalkylene is not only desirably compatible with the styrene resin component as much as possible, but also polyalkylene with a very high melting point is not preferable in order to achieve the desired value for the fusion temperature. It is preferable to have a low molecular weight, with a weight average molecular weight of about 100
Polyalkylenes having a weight average molecular weight of approximately 2,000 to 6,000 can be effectively used in the present invention.

Further, these polyalkylenes having a softening point of 100 to 180°C, particularly 130 to 160°C are effective.

The polyalkylene having a weight average molecular weight of 1,000 to 45,000 according to the present invention includes polyethylene, polypropylene, polybutylene, etc., and polypropylene is particularly effective.

If the weight average molecular weight of the polyalkylene is less than 1,000, the softening point will be low, resulting in toner aggregation and contamination of the photoreceptor and carrier, which is undesirable.
If it exceeds 5,000, the softening point becomes too high and is no longer effective in preventing offset.

The amount of polyalkylene contained in the toner varies depending on the resin components of the toner, the types of colorants and toner additives, and their usage amounts, but is generally 1 to 25 parts by weight, preferably 1 to 25 parts by weight per 100 parts by weight of the resin components of the toner. The amount is 2 to 10 parts by weight, and if it is less than 1 part by weight, the effect will be small, and if it exceeds 25 parts by weight, it will have an adverse effect on the chargeability and fluidity of the toner, which is not preferable.

In order to incorporate polyalkylene into the toner, it may be added during premixing of the resin component, colorant, and various toner additives prior to the kneading step.

Any suitable pigment or dye can be used as a colorant in the toner of the present invention.

For example, carbon black, nigrosine dye (C,1
, A30415B), aniline blue (C,1,A30
405), Calco Oil Blue (C, 1, Aazoec
Blue 3), Chrome Yellow (C,1,%1
4090), ultramarine blue (C, 1, A771
03), DuPont Oil Red (C, 1, 26105
), quinoline yellow (C,1,447005), methylene blue chloride (C,I.

A32015), Phthalocyanine Blue (C, I.

474160), malachite green oxalate (C
, 1,442,000), lamp black (C, 1, A
77266), Rose Bengal (C, I.

A45435) and mixtures thereof, which must be present in the toner in an amount sufficient to color the toner so that it can be developed to form a visible image.

Since the toner of the present invention has the above-mentioned structure, even in the case of a heating roller fixing device that does not supply an offset prevention liquid, it is possible to efficiently and efficiently fix the heating roller without causing an offset phenomenon or a wrapping phenomenon of the transfer sheet. can be done.

This is because when polyalkylene, which is a component of the toner of the present invention, is heated, it becomes a liquid with low viscosity, so when a toner containing this comes into contact with a heated fixing roller, the polyalkylene in the toner becomes axillary. The toner is released on the surface and coats the surface of the fixing roller, making it difficult for the melted toner to adhere to the fixing roller surface due to the releasability of polyalkylene itself. Even if the toner adheres to the fixing roller, since the toner uses a polymer with high elasticity when melted and a Mw/Mn of 3.5 or more as a component of the toner, its elasticity allows the toner attached to the fixing roller to be transferred from the fixing roller to the transfer sheet, etc. This is because it can be pulled back onto the toner support.

In order to make a polymer more elastic when it is melted, conventional methods have been to increase the molecular weight of the polymer or to increase the degree of entanglement between molecular chains by crosslinking the polymer. However, polymers that have been made high in molecular weight or crosslinked to the point where effective non-offset properties are obtained generally have a high softening point and high toughness, which makes it difficult to use in post-development fixing steps and toner There was a drawback that a large amount of energy was required in the pulverization process during production.

However, a polymer with a wide molecular weight distribution has a low molecular weight part and a high molecular weight part or a crosslinked part within the same polymer, so a toner made from such a polymer has
Its low molecular weight portion ensures fixability and crushability, and at the same time, its high molecular weight portion or crosslinked portion provides non-offset properties.In particular, both of these properties are dependent on the number average molecular weight (Mn) of the polymer. Weight average molecular weight (M
In a polymer in which the value of the ratio Mw/Mn of w) is 3.5 or more, both are always obtained at the same time.

As described above, the toner of the present invention contains a styrene polymer having an Mw/Mn of 3.5 or more or a copolymer of a styrene monomer and other vinyl monomer, and a release agent by weight among various mold release agents. By using polyalkylene having an average molecular weight of 1,000 to 45,000 in combination, the synergistic effect can significantly improve the non-offset property of the toner, and also prevent the transfer paper from wrapping around the fixing roller.

In addition, the effect of preventing offset phenomenon and wrapping phenomenon can be achieved not only by fixing rollers whose surfaces are made of a release material, but also by fixing rollers whose surfaces are made of metal, which is generally considered to have no releasing properties. It is also allowed when using.

Therefore, by using the toner of the present invention, it is easy to prevent toner offset and wrapping phenomena even without using a fixing roller whose surface is made of a releasable material, which is extremely important in terms of device design. It's advantageous.

The effect of adding polyalkylene to the toner is not only to improve the release properties as described above, but also to improve the dispersibility of colorants such as nigrosine and other additives contained in the toner, thereby improving the charge control properties of toner particles. It also has the effect of making it uniform and improving its performance as a developer.

The electrostatic charge effect toner of the present invention has the styrene resin and low molecular weight polyalkylene according to the present invention as main resin components as described above, and not only the resin according to the present invention as a resin component. , other resins can be mixed and used as needed.

Other resins that can be mixed and used include α
, resins consisting of β-unsaturated ethylenic monomers, those that do not contain α, β-unsaturated ethylenic monomers as a monomer component, such as rosin-modified phenol-formalin resins, epoxy resins, polyurethane resins, cellulose resin,
Non-vinyl resins such as polyether resins can be mentioned.

These resins include the type of resin according to the present invention used as the main resin component of the toner, for example, the type of monomer that is a constituent component of the resin, and the copolymer when it contains a copolymer. The appropriate amount can be adjusted to achieve desired physical properties and physical properties of the toner depending on the copolymerization ratio of each monomer in combination, the molecular weight of the resin, the softening point of the resin, the glass transition point of the resin, etc. It is used by selecting and determining the amount of mixture.

For example, even if the resin according to the present invention used as the main resin component of the toner is sufficient in that it can prevent the toner offset phenomenon, for example, it is too soft and has poor pulverization properties in toner production. In some cases, other characteristics required for toners such as insufficient triboelectric charging properties, lack of stability, or tendency to form clumps when made into toners are not necessarily sufficient. In such cases, for example, By selecting a xylene resin as the other resin to be mixed, the above-mentioned drawbacks can be improved and a toner having good properties can be obtained.

On the other hand, if the resin according to the present invention used as the main resin component of the toner consists only of polystyrene, it tends to be a little too brittle and easily becomes fine when crushed. By mixing these, the physical properties can be improved.

The toner of the present invention can effectively prevent the toner offset phenomenon by using the resin according to the present invention as a resin component, but in order to further suppress the occurrence of the toner offset phenomenon, if necessary, The toner can contain various compounds that impart release properties and anti-wrapping properties to the toner.

These compounds include, for example, cadmium, barium, lead, nickel, cobalt, copper, strontium, calcium or magnesium salts of stearic acid, zinc, manganese, iron and cobalt salts of oleic acid. salts, copper salts, lead salts or magnesium salts, zinc salts, cobalt salts, copper salts, magnesium salts, aluminum salts or calcium salts of palmitic acid, zinc salts, cobalt salts or calcium salts of linoleic acid, zinc salts of ricinoleic acid or Fatty acid metal salts such as cadmium salts, lead salts of caprylic acid, lead salts of caproic acid, higher fatty acids having 17 or more carbon atoms, higher alcohols, natural or base paraffins, fatty acid esters or their partial Examples include alkylene bis fatty acid amides such as ethylene bis stearoyl amide, esters of polyhydric alcohols, and these compounds may be contained in the toner either alone or in an appropriate combination of two or more thereof.

The amount of these compounds added to the toner is generally about 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of the resin component of the toner. This also improves the dispersibility of other toner additives such as colorants and charge control agents in the resin component.

In addition, if the resin component has relatively brittle properties, it is possible to prevent excessive pulverization during the pulverization process during toner production, and it is possible to obtain particles of the desired particle size in high yield. I can do it.

Furthermore, the stability of the toner is increased, and the triboelectricity does not change even during long-term use, so that the life of the toner can be significantly extended.

Note that the toner of the present invention may contain a charge control agent, if necessary.
Various other toner additives such as plasticizers can be included.

The toner image formed on the fixing sheet using the toner of the present invention has a surface area (the surface of the toner image formed on the fixing sheet). It is possible to efficiently perform good heating roller fixing without any problems.

The surface of the fixing roller may be made of, for example, Teflon (manufactured by DuPont), FEP (manufactured by DuPont), Fluon (I
CI), KEL-F (manufactured by 3M), Diflon (manufactured by Daikin, etc.) or KE-130ORT
A material having a smooth surface made of relatively hard silicone rubber such as V (manufactured by Shin-Etsu Chemical Co., Ltd.), or a material having a metal surface in some cases can be effectively used.

Generally, when producing a toner, a resin component, a colorant component, and an additive component are mixed and then kneaded using a kneading machine.

The bulk toner composition obtained by kneading is then crushed and sieved to obtain a toner having a desired particle size.

The toner particle size removed through sieving is kneaded again using a grinder, pulverized, and subjected to repeated sieving to obtain toner having a desired particle size, and these steps are repeated. This will improve the overall yield.

However, the mixing process using a kneading machine applies shearing force to the resin components in the toner, which may break the resin chains and change their structure and molecular weight.

For this reason, even if the molecular weight of the styrenic resin according to the present invention changes slightly due to the initial kneading step, the objective of the present invention can be achieved by maintaining the Mw/Mn value of 3.5 or more, but the yield By repeatedly performing kneading steps for improvement, the molecular weight of the styrenic resin may gradually change, and for example, the value of Mw/Mn may decrease to 3.5 or less.

In such a case, it is no longer possible to obtain a toner that achieves the object of the present invention, and the yield decreases.

Yield is one of the important factors in the production of toner, and among the resins of the present invention, especially those having a Mw/Mn value of 5 or more, even after repeated kneading steps, the value does not decrease to 3. .5
Since it is unlikely to change outside the following range, it has the advantage that the yield in toner production can be significantly improved.

Therefore, from this point of view, in the present invention, Mw/
It is particularly desirable to use a resin with Mn of 5 or more.

Next, the present invention will be illustrated by examples, but the embodiments of the present invention are not limited thereto.

In the Examples, the number of copies is expressed by weight unless otherwise specified.

Example 1 Styrene-n-butyl methacrylate [7:3 copolymer Mw29X10', Mn: lXlO4°Mw/
Mn: 9) 100 parts, polypropylene (Mw:
3X103) 5 parts, carbon black 10 parts and nigage-causing thin base EX (CI//6504.15B) 2
The mixture was mixed and subjected to a ball mill for about 24 hours, then kneaded using a heated roll, cooled, and ground to produce a toner having an average particle size of about 13 to 15 microns, which was used as a sample.

Four parts of these toners are mixed with 96 parts of iron powder carrier having an average particle size of about 50 to 80 microns to form a developer, and this developer is used to form electrostatic images by conventional electrophotography. After development, the toner image is transferred onto transfer paper, and the surface is bonded with a fixing roller whose surface is made of Teflon (manufactured by DuPont, polytetrafluoroethylene) and whose surface is made of silicone rubber KE1300RTV (manufactured by Shin-Etsu Chemical Co., Ltd.). Using a roller, the temperature of the fixing roller was varied at a linear speed of 150 mm/sec, and the toner image was brought into pressure contact and fused and fixed.

Next, in order to investigate whether the fused toner image would be transferred to the surface of the fixing roller and cause an offset phenomenon, after repeated fixing operations, transfer paper without toner images was placed on the fixing roller under the same conditions as above. The transfer paper was brought into pressure contact and dirt caused by toner offset on the transfer paper was observed.

As a result, when the sample toner was used, slight staining due to toner offset was observed on the transfer paper at 24.0° C., but no wrapping of the transfer paper around the fixing roller occurred.

Example 2 Polystyrene (A1) (Mn: 8) was used instead of styrene-n-butyl methacrylate in the sample of Example 1.
300, Mw/Mn: 4.5, softening point by ring and ball method (hereinafter referred to as BAR); 125°C, glass transition point T or less
g): 97°C] and polystyrene (A2) (Mn:
5000, Mw/Mn: 25.

A toner sample was prepared in the same manner as in Example 1, except that B&R: 135°C, Tg: 95°C] was used.

When this toner sample was examined for toner offset properties in the same manner as in Example 1, slight staining due to toner offset was observed on the transfer paper at 210°C, but no wrapping of the transfer paper around the fixing roller occurred. There wasn't.

Example 3 In the sample of Example 1, styrene-methyl methacrylate-butyl methacrylate [5:2:3 copolymer, Mn] was used instead of styrene-〇-butyl acrylate.
: 98000, Mw/Mn: 6.5, B&R
A toner sample was prepared in the same manner as in Example 1 except that the temperature was 140'C, Tg: 72°C].

When this toner sample was examined for toner offset properties in the same manner as in Example 1, no offset occurred on the transfer paper even at 250° C., and no wrapping of the transfer paper around the fixing roller was observed.

Example 4 In the sample of Example 1, polypropylene (Mw: 3X1
03) instead of polypropylene (Mw: 4.5X
A toner sample was prepared in the same manner as in Example 1 except that 10') was used.

When this toner sample was examined for toner offset properties in the same manner as in Example 1, a slight offset was observed on the transfer paper at 200°C, but it was not to the extent that it would be a problem in practice, and it No wrapping of the transfer paper occurred.

Example 5 Two parts of fatty acid ester were further added to the formulation of Example 1, and the toner offset property was examined in the same manner as in Example 1. A slight stain due to the toner offset phenomenon was observed on the transfer paper at 250°C. However, no wrapping of the transfer paper around the upper fixing roller occurred.

Comparative Example 1 In the sample of Example 1, styrene-n-butyl methacrylate (Mw: 2.5 X 10', Mn: 9X) was used instead of styrene-n-butyl methacrylate.
A toner sample was prepared in the same manner as in Example 1, except that a sample of 10", Mw/Mn: 2.8) was used.

When this toner sample was examined for toner offset properties in the same manner as in Example 1, significant offset was observed on the transfer paper at 170° C., and the transfer paper was also wrapped around the fixing roller.

Comparative Example 2 A toner sample was prepared in the same manner as in Example 1 except that polypropylene (Mw: 800) was used instead of polypropylene in the sample of Example 1.

When a sample of this toner was used to examine the offset properties of the toner in the same manner as in Example 1, it was found that the surface of the photoreceptor and the carrier were so contaminated that the toner could not be used.

Furthermore, when this toner was stored, it agglomerated and became unusable.

Comparative Example 3 A toner sample was prepared in the same manner as in Example 1 except that polypropylene (Mw: 60,000) was used instead of polypropylene in the sample of Example 1.

A sample of this toner was examined for toner offset properties in the same manner as in Example 1, and significant offset was observed on the transfer paper at 180° C., and the transfer paper was also wrapped around the fixing roller.

Comparative Example 4 A sample was prepared using the same amount of zinc stearate in place of polypropylene in the sample of Example 1, and the offset property of the toner was investigated in the same manner as in Example 1. This was observed, and the transfer paper was also caught around the fixing roller.

Table 1 shows the results of studies on various mold release agents.

Comparative Example 5 A sample was prepared by removing polypropylene from the formulation of Example 1, and the offset property of the toner was examined in the same manner as in Example 1. It was found that significant offset occurred on the transfer paper at 170°C, and the fixation was poor. The transfer paper also became wrapped around the upper roller.

Comparative Example 6 In the sample of Example 1, styrene-n-butyl methacrylate (Mw: 2.5 XiO') was used instead of the styrene-n-butyl methacrylate copolymer.

Mn: 9 x 103. Mw/Mn: 2.8
), and a sample was prepared by removing polypropylene from the formulation of Example 1, and the offset property of the toner was investigated in the same manner as in Example 1. It was found that a significant offset phenomenon had already occurred on the transfer paper at 120°C. In addition to this, severe wrapping of the transfer paper around the upper fixing roller also occurred, so that no fixed image could actually be obtained.

Table 1 shows the temperature at which offset occurs and the presence or absence of wrapping of the transfer paper around the fixing roller when various types of abrasion are used.

Toner is the same as Example 1 (excluding molding agents).

toner (however, it is

Claims (1)

[Scope of Claims] 1. Styrenic polymers having a weight average molecular weight/number average molecular weight of 3.5 or more or copolymers of styrene monomers and other vinyl monomers, and weight average molecular weights of 1000 or more.
45,000 polyalkylene in an amount of 1 to 25 parts by weight per 100 parts by weight of the resin component. 2. The electrostatic latent image on the image forming member is formed using a styrenic polymer or a copolymer of a styrene monomer and another vinyl monomer having a weight average molecular weight/number average molecular weight of 3.5 or more, and a weight average molecular weight/number average molecular weight of 3.5 or more. An image forming method characterized by forming a toner image using a toner containing 1 to 25 parts by weight of polyalkylene having a molecular weight of 1,000 to 45,000 per 100 parts by weight of the resin component, transferring the toner image to a transfer medium, and then fixing it with a heated roller. .